New research

Scientists dig deep into earth's history for clues to El Niño past, present and future

  • 26 Nov 2014, 18:00
  • Roz Pidcock

The Pacific weather phenomenon known as El Niño has attracted a lot of attention this year as forecasters have puzzled over its 'will it or won't it' behaviour.

In May, scientists were confidently predicting a  90 per cent chance of an El Niño materialising by the end of the year. But it's proved elusive, with the odds of even a weak event dropping to 58 per cent earlier this month.

El Niño brings extreme rainfall to some parts of the world and drought to others. So predicting when one will make an appearance and how big the effects will be is important.

A new study just published in Nature uses a diverse array of different data sources, from corals to computer modelling, to unravel what's been driving changes in El Niño over the past 21,000 years.

Pinning down this  enigmatic phenomenon is tricky, the study concludes. But there's reason to believe climate change could lead to stronger El Niño's in the future, say the scientists.

El Niño and climate-readiness

Every five years or so, a change in the winds causes a shift to warmer than normal ocean temperatures in the  equatorial Pacific Ocean - a phenomena known as El Niño.

Together, El Niño and its cooler counterpart La Niña are known as the El Niño Southern Oscillation (ENSO). Cycling between the two phases is responsible for much of the variation we see in global climate from one year to the next.

Knowing if and how climate change will affect El Niño and La Niña is an important scientific question, says Professor Kim Cobb, co-author on today's paper. She  told us recently:

"Preparing for large swings in temperature and rainfall is critical to adaptation strategies, especially if such variability will increase in the future."

In theory, human-caused warming could increase the strength of ENSO events, Cobb continues:

"It is important to remember that climate change is much more than "global warming" … Because ENSO involves feedbacks between the wind strength, ocean temperature, and circulation, a change in any related climate parameter would arguably have some effect on ENSO strength".

more

Remote-controlled submarines reveal Antarctic sea ice is thicker than previously thought

  • 24 Nov 2014, 16:14
  • Robert McSweeney

New research sees scientists using remote-controlled submarines to create 3D maps of Antarctic sea ice. And the results suggest sea ice is thicker than previously thought.

The area covered by Antarctic sea ice appears to be slightly growing each year, the reasons for which are proving hard to pin down. Today's research adds another dimension to unravelling the complex goings-on around the South Pole.

Measuring ice thickness isn't easy

Scientists have been monitoring changes at Earth's poles for decades now. But the harsh conditions of the Antarctic make it difficult to get good measurements of the sea ice that surrounds the vast continent.

How and why Antarctic sea ice thickness is changing "remains one of the great unknowns in the climate system," says Dr Ted Maksym of the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.

While satellites are very good at measuring the extent, or area, of sea ice covering the ocean, they struggle when it comes to ice thickness. Satellite measurements can't distinguish between ice and the snow lying on top of it, which makes it harder for scientists get accurate readings of its true depth.

Scientists can also make estimates of thickness from visual observations or by drilling into the ice itself. But these approaches are hampered by thick sea ice during winter and spring, which prevents ships from accessing parts of the Antarctic coast.

To overcome these limitations, Dr Maksym and his colleagues deployed 'Autonomous Underwater Vehicles (AUVs)', which are specially-designed unmanned submarines that measure ice thickness to within 10 centimetres.

The data from these submarines, published in  Nature Geoscience, suggests that Antarctic sea ice is thicker than previously thought.

more

Tackle air pollution to kickstart climate action, says new study

  • 19 Nov 2014, 18:00
  • Roz Pidcock

Air pollution is a huge problem worldwide, killing millions of people each year. Further warming will only increase the size of the problem, according to a Nature article today.

It's time efforts to curb soot, ozone and other pollutants in the atmosphere got more attention at an international level, the researchers argue.

Getting serious about air pollution could provide the impetus needed to tackle climate change more effectively.

Airborne killers

Methane, ozone, nitrogen dioxide and soot (or black carbon) all contribute to poor air quality.

Air pollution is already the  leading environmental cause of ill-health, leading to about seven million premature deaths each year from respiratory and circulatory illnesses.

Earlier today, the European Council  ruled the UK must take urgent action to address dangerous levels of air pollution. A number of major cities, including London, are lagging behind targets to reduce nitrogen dioxide to legal limits by the January 2015 deadline.

The burden of ill-health is  likely to increase in cities by mid century, as air pollution interacts with further greenhouse gas warming, research shows.

Compounds Of Concern _Schmale

Impacts of common air pollutants for human health, the climate and agriculture. Source: Schmale et al. (2014)

more